The objective of this research proposal is to delineate differences in the regulation of cell division between lymphocytes obtained from healthy donors and from patients with chronic lymphocytic leukemia (CLL). The role exerted by cyclic AMP in relationship to cell growth induced by mitogens was investigated in both cell types. The intracellular levels of cyclic AMP were 3-fold greater in normal lymphocytes than in CLL cells. Furthermore, the cycle AMP levels fluctuated as a function of cell division in normal lymphocytes but not in the leukemic ones. Sodium periodate was also explored as a mitogenic stimulus of lymphocytes. This agent stimulated both normal and CLL lymphocytes to divide, at least partially, through the release (or production) of a lymphocyte growth factor. These studies provide new insights into how cell division is controlled in lymphoid cell populations.